Thread:Hayds126/@comment-32069757-20180615233225/@comment-35468293-20180717003345

Battle Resost can be accessed post-game when you get the S.S. Ticket from your Dad after beating Zinnia and getting Rayquaza. You go to Slateport and tell the guy to take you there.

To reset EVs, you would need to get the reset berries that raise friendship but lower something like Attack or Sp. Defense. Or you can go to Super Training and get a Reset Bag from randomly punching, which resets all Evs.